RESUMO
This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo-catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950 °C for 4 h. BBT is characterized by an X-ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29 eV, which comes in the photon energy range of ultra-violet radiation. BBT powder is poled by using Corona poling in the presence of 2 kV mm-1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo-piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo-piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species.
RESUMO
Utilizing mechanical energy to produce hydrogen is emerging as a promising way to generate renewable energy, but is challenged by low efficiency and scanty cognition. In this work, graphitic carbon nitride (g-C3 N4 ) with an atomically thin sheet-like structure is applied for prominent piezocatalytic and photo-enhanced piezocatalytic H2 production. It is revealed that the anomalous piezoelectricity in g-C3 N4 originates from the strong in-plane polarization along the a-axis, contributed by the superimposed polar tri-s-triazine units and flexoelectric effect derived from the structured triangular cavities, which provides powerful electrochemical driving force for the water reduction reaction. Furthermore, the photo-enhanced charge transfer enables g-C3 N4 nanosheets to reserve more energized polarization charges to fully participate in the reaction at the surface reactive sites enriched by strain-induced carbon vacancies. Without any cocatalysts, an exceptional photo-piezocatalytic H2 evolution rate of 12.16 mmol g-1 h-1 is delivered by the g-C3 N4 nanosheets, far exceeding that of previously reported piezocatalysts and g-C3 N4 photocatalysts. Further, high pure-water-splitting performance with production of the value-added oxidation product H2 O2 via photo-piezocatalysis is also disclosed. This work not only exposes the potential of g-C3 N4 as a piezo-semiconductor for catalytic H2 evolution, but also breaks a new ground for the conversion of solar and mechanical energy by photomediated piezocatalytic reaction.